The present invention relates to a laser cutting system that has new designs at least with respect to its frame, its laser output mechanism, the process of outputting the laser for fabricating a worksheet, and the worktable system to which the worksheet is placed.
Flying optic laser cutting systems are known. However, the prior art systems tend to have a number of shortcomings that limit their speed and efficiency. Some of these shortcomings result from, for example, the design of the frame that supports the cutting head of the laser cutting system, the design of the cutting mechanism itself, the way in which the cutting process is effectuated, the limited way in which a machine may be installed and, once installed, the limited accessing of the machine by the operator.
The laser cutting system of the instant invention aims to improve on every aspect of the aforenoted shortcomings of current laser cutting systems by, specifically, providing a new frame for the system, an improved laser cutting mechanism, and a more efficient process of effecting cutting. In addition, the laser cutting system of the instant invention is provisioned with a worktable system that enhances the cutting of a worksheet placed thereon, as well as for evacuating any dust and/or exhaust gases resulting from the fabricating of the worksheet efficiently away from the laser cutting system.
The present invention laser cutting system is built on a frame that has a cross beam supported by two structures. The cross beam is designed to have a trapezoidal structure for movably supporting a laser cutting head that hangs therefrom. The laser cutting head in turn is mounted to a base member that has arms extending in a direction perpendicular to the longitudinal axis of the cross beam. As a consequence, the cutting head can move along the longitudinal axis of the cross beam as well as the longitudinal direction along the axis of the arms extending from the base member. To effect the movement of the base member bidirectionally along the longitudinal axis of the cross beam, a linear drive mechanism, in the form for example of a magnet drive, may be used. A linear drive may also be used for moving the cutting head along the direction of the extending arms of the base members. For the movement of the cutting head along the vertical direction, a servomotor is mounted to the base member, or more specifically the skeleton frame of the base member to which the cutting head is mounted, so that the cuffing head can be moved in a direction perpendicular to the respective longitudinal axes of the cross beam and the extending arms.
The cross beam of the frame of the laser cutting system is supported, at both ends, by respective support structures, which may be unitary structures. One the structures is configured to have a bore through which exhaust gases and/or dust particles resulting from the fabricating of a worksheet by the laser beam output from the cutting head may be vented away from the laser cutting system. The other of the support structures is configured to have an opening through which worksheets may be conveyed to or removed from a support table, such as for example a worktable or a cassette placed underneath the cross beam. The worksheets may also be conveyed to/from the laser cutting system from either side of the cross beam in a direction perpendicular to the longitudinal axis of the cross beam. To provide further rigidity for the frame of the laser cutting system, two truss members connect the support structures at their respective bases.
To control the movement of the laser cutting head, a processor means, such as for example a computerized numerical controller (CNC), is provided in a housing positioned relative to the frame. The CNC, in addition to controlling the respective movements of the various drive motors that move the cutting head along the various directions, also controls the outputting of the laser beam to the cutting head by the laser generator, which is also positioned adjacent and/or relative to the frame.
For the laser cutting system of the instant invention, the laser beam output from the laser beam generator, or resonator, is reflected by a number of mirrors with the focal point of the laser beam for fabricating the particular material of the worksheet to be focused by a motor mechanism internal to the cutting head. To maintain the distance related to the widening or focusing of the axial symmetric laser beam, the laser generator of the inventive laser cutting system has a telescope mechanism, positioned within the laser generator itself, that works cooperatively with the output coupler of the laser resonator for maintaining the density and the power of the laser beam to constant values for a predetermined distance, so that the power of the laser beam requisite for effectively fabricating the worksheet is maintained for every portion of the worksheet. The telescope mechanism has two mirrors. One is the output coupler from the laser resonator. The other is the lens that moves relative to the output coupler. The lens is driven relative to the coupler by a motor, which is controlled by software of the system according to some preset parameters. These parameters include, among other things, the distance separating the lens from the sheet material, i.e. the focusing lens distance.
Such auto-focusing of the laser beam is done automatically by a cognizance of a predetermined distance that the laser beam is to be output, the type of material being fabricated, and the type of telescopic mechanism to be used. Moreover, by taking into consideration the actual length of the laser beam and by dividing the maximum useable length of the laser beam into a number of zones, i.e., different quadrants or sectors, the focal point of the laser beam may be corrected. The focus of the laser beam for the different areas of the worksheet may be adjusted by moving the laser cutting head bidirectionally along its vertical axis to maintain respective optimal focal points for worksheets of different materials.
To compensate for the deficiencies inherent in the different areas of the worksheet which may be due to their respective locations with reference to the center of the worksheet, the worktable or cassette onto which the worksheet is placed has its areas divided into a number of portions each with correction factors determined empirically, so that such correction factors may be taken into account when a particular location of the worksheet which corresponds to the location on the worktable to which that portion of the worksheet superposes is to be fabricated by the laser beam output from the cutting head. These correction factors are stored in a memory that may be part of the CNC controller.
With respect to the way in which the laser beam output from the laser generator is to be directed, a number of reflective mirrors are used. To enhance the alignment process, unlike the prior art systems that require extensive removal and reassembly of the various mirrors for alignment of the laser beam, the reflective mirrors of the instant invention laser cutting system are configured such that alignment can easily be effected by the removal of a single one of the mirrors. Further, the reassembly of the mirror into the system does not require any further realignment of the laser beam. This is done by configuring the opening of the mirror holder to have a dimension large enough to allow the removal of the mirror while leaving the mirror holder fixed to the support of the device and allowing the laser beam to freely pass.
The laser cutting head being used with the laser cutting system of the instant invention, but for a number of modifications, could be any cutting head that is sold by a number of manufacturers. One of the improvements of the cutting head of the instant invention is the provision of a servomechanism, via feedback, for automatically adjusting the focus lens inside the cutting head so as to enable the automatic adjustment of the focus point for different types of materials that may be fabricated by the laser beam output from the cutting head. Another improvement of the cutting head of the instant invention is the provision of a partition window somewhere within the cutting head for isolating the focusing lens from particles that may ricochet against the focusing lens when the worksheet is being pierced or cut by the laser beam. This is particularly true when the laser process is not stable or when the parameters for cutting are not set properly. Such partition means may be in the form of a diamond window that has the properties of being translucent so as to allow the laser beam to pass therethrough as well as having the hardness for withstanding the impacts of the ricocheting particles. Other partition windows that have the same qualities as a diamond window may also be used.
To enhance the fabrication of a worksheet, the movement of the cutting head and the directing of the laser beam thereto are controlled by the CNC in a process that takes into consideration the distance separating a location on the worksheet for which work is being done to a next location on the worksheet to which the next piercing by the worksheet is to be effected. To effect the optimal movement of the cutting head from one location to the next, variables such as acceleration and deceleration of the cutting head, the height of the cutting head with respect to the cutting sheet, or the focal point for the material to which the worksheet is made of, are taken into consideration. The movement of the cutting head relative to the worksheet may be termed a xe2x80x9cping pongxe2x80x9d effect in that the cutting head moves in an optimal manner from point to point for piercing various holes and cuts on the worksheet.
The worktable onto which the worksheet is placed is made up of a frame, in the shape of a cassette, that is movable in directions perpendicular to the longitudinal axis of the cross beam. The movement of the cassette is effected on a couple of rails, or guides, onto which the cassette rides. Within the cassette there are a number of strips, each having a number of bores formed therealong extending along the length of the cassette. A number of brackets extend in a direction perpendicular to the strips at predetermined positions along the cassette. These brackets each have a number of equally spaced slots formed therealong. A plurality of ribs are fitted to equally distanced slots of the brackets so that the ribs and the strips that have the bores are alternated throughout the cassette along its longitudinal direction. The ribs each are formed with a number of contiguous teeth at its top portion. Into each bore of each strip a pin is inserted. The plane that is formed by the tips of the pin is higher, although not by much, than the plane that is formed by the tip of the contiguous teeth of the ribs. Thus, it is the tip of the pins that support the worksheet on the cassette. If the worksheet flexes, or when the worksheet is being cut, the tips of the contiguous teeth of the ribs would provide support for those portions of the worksheet that fall below the plane formed by the tips of the pins.
By being able to roll along the rails, the cassette is movable between a location under the cross beam for the fabrication of a worksheet placed thereon, and a location that is away from the frame of the laser cutting system, so that the finished worksheet may be removed, and be replaced by a to be fabricated worksheet.
The cassette is placed over a suction frame structure that has a number of sections each adaptable to provide vacuum to a corresponding portion of the cassette. Thus, by activating the particular section of the suction base, particles resulting from the fabrication of the worksheet by the laser beam are suctioned away and vented through the bore at one of the support structures of the frame away from the laser cuffing system.
It is therefore an objective of the present invention to have a frame designed for providing a more efficient way of mounting a cutting head for a laser cutting system.
It is another objective of the present invention to provide a laser cutting system that has an improved laser resonator having means that can provide auto-focusing.
It is yet another objective of the present invention to provide an improved cutting head for a laser cutting system that does not require its focusing lens to be replaced as often as those in conventional laser cutting heads.
It is still another objective of the present invention laser cutting system to provide a process of more efficiently moving the cutting head.
It is still yet another objective of the present invention to provide a worktable that enhances the fabrication of a worksheet placed thereon by a laser beam.
It is therefore an overall objective of the present invention to provide a flying optic laser system that operates in a way that is more efficient than prior art laser cutting systems.